Structural support for freeways, bridges and large buildings usually requires placement of a series of concrete piles, where pile is defined as a slender, deep foundation unit, entirely or partially embedded in the ground. The concrete pile is reinforced by a steel cage of rebar. The purpose of the pile is to transfer heavy axial or lateral loads to a deep stratum below the ground surface. To test the quality of the concrete piles, testing tubes with testing probes are inserted prior to the pour of concrete. The prior art involved ad hoc methods for securing the testing tubes to the rebar cage. Our improvement on the prior art involves uniform method for quickly and safely snapping a first pre-formed device onto each of the tubes, connecting the first device to a second pre-formed device, which second device is then snapped onto the rebar.
One common pile design is referred to as Cast-in-Drilled Hole (CIDH). The CIDH pile is a cylindrical shaft at least two feet in diameter, with a length necessary to accommodate the particular needs of a construction project which length could be substantially greater than 30 feet.
The first step in placement of the CIDH pile is to drill a hole in the ground. After the hole is drilled, the second step involves building a cylindrical rebar (“reinforcing bar”) cage or steel skeleton to provide reinforcement for later to be poured concrete. The third step is to insert hollow PVC or iron or metal alloy testing tubes into the cage. The purpose of the tubes is to accommodate testing probes which are used to measure the quality of the concrete pour. The fourth step is to affix the tubes to the cage so that the tubes remain in designated positions during the concrete pour. The fifth step is to place the cage with the tubes into the hole. The sixth step is to pour concrete into the hole. The final, seventh step involves insertion of Cross-hole Sonic Logging (CSL) or Gamma-Gamma Logging (GGL) testing probes into the tubes. The CSL or GGL are used to detect anomalies or defects in the poured concrete.
The prior art construction techniques involved affixing the testing tubes to the rebar cage by use of baling wire or other unspecified, ad hoc coupling techniques. See for instance, Alter U.S. Pat. No. 9,074,473 (Jul. 7, 2015) which relied on hollow rebar tubes to house the CSL or GGL probes: “hollow rebar may provide continuous access tube segments that can be coupled to any required length, and the couplings may be watertight with rubber seals to prevent leakage,” (3:54-57). The coupling of tubes and rebar was only vaguely identified, except to acknowledge the necessity of watertight couplings.
Prior art recognized that the tubes must be positioned in a circle at designated intervals, parallel to the longitudinal axis of the drilled shaft to insure complete coverage for testing the concrete within the shaft. Whether the testing method involved sound echo, radiation or temperature changes to detect anomalies, pre-positioning of the tubes is important to make sure there are no gaps in coverage. See for example, Mullins U.S. Pat. No. 6,783,273 (Aug. 31, 2004): “The spacing and number of logging tubes is selected such that the frequency of tubes provides sufficient information to detect defects within both the core and the protective cover,” (2:22-24).
The testing tubes have uniform outer diameters for use in CIDH piles, for instance 2¼″. This uniform diameter feature accommodates a prefabricated, mass produced device for securing and stabilizing testing tubes (hereafter “securing device”) within the rebar cages in CIDH piles. The securing device can be quickly and safely affixed to the testing tubes.
Similarly, rebar have uniform outer diameters for use in CIDH piles, typically ranging from ½″ to ⅞″ diameter. Once again, the uniform diameter feature accommodates a prefabricated, mass produced device for attachment to the longitudinal rebar, within the rebar cages in CIDH piles.
The need for complete coverage in the placement of testing tubes to insure sufficient information about the concrete can be obtained after the pour, along with the need to quickly and safely insert the tubes within the rebar cage, and to tie the tubes to the cage can be met by prefabricated devices which easily snap onto the tubes or slide onto the tubes, where the devices can be connected to one another, and then the devices can be snapped onto and be tied to a longitudinal piece of rebar in the cage.